The British prime minister may have thought Brexit and the Irish border was her most difficult issue on the island of Ireland; but now she has another - Northern Ireland's abortion ban.

As the result landed in Dublin, back in the UK the women and equalities minister Penny Mordaunt was beginning a campaign of her own.

"A historic and great day for Ireland, and a hopeful one for Northern Ireland. That hope must be met," she tweeted.

A naked challenge from the current women's minister to a former one - Theresa May. The campaign started on the backbenches by Stella Creasy to give one million Northern Irish women access to abortions at home has found its way into her cabinet.

Image:Theresa May will be loath to spend political capital on abortion law

In the UK, 130 MPs have already said they will back an amendment to the domestic violence bill to give Northern Irish women the same rights as other British women have enjoyed since the abortion act was passed in 1967.

Mrs May is loath to get involved; her government is clear that this is a devolved issue.

She's also loath to get involved for fear of antagonising the anti-abortion DUP and destabilising her fragile minority government even further.

She has to get Brexit and the Irish border issue through and doesn't want to use any political capital on abortion rights.

There's a cross community majority in Northern Ireland for abortion law reform, but the people don't even have an assembly in Stormont, let alone the political will to look at the matter in the face of Dublin's vote.